1. Field of the Invention
This invention relates to safety latches for hooks used in hoisting cargo and the like and more particularly to an improved safety latch structure suitable for use on grab hooks adapted to receive link type chain as well as on conventional lifting hooks adapted to receive cables and the like.
2. Description of Related Art
The use of safety gates or latches on lifting hooks of conventional design is well known in the prior art. Such gates or latches have generally been mounted for rotation about the axis of the shank of the hook from a closed position extending across the throat of the hook to an open position extending to one side of the throat to allow insertion or removal of a cable or the like. Such gates or latches must be opened manually for both insertion and removal of a cable or the like. In their open position, such gates or latches project from one side or the other of the hook.
Many of the gates or latches known in the prior art have been designed to close automatically as by spring loading. However, they have also required some means for locking them in their closed position and thus they have included multiple parts and mechanisms which added cost and complication in manufacture as well as making them prone to damage in use.
The gate or latch structures of the prior art have not been suitable for use on "grab" hooks. Grab hooks are designed to snugly receive both sides of one link of a conventional chain, thus locking the hook between the two adjacent links of the chain to avoid slippage of the hook along the chain. A gate or latch structure which projects from the side of a hook in its open position will tend to interfere with one of the links of the chain adjacent the link to be received in the hook. Such interference will tend to result in damage to the gate or latch under heavy load conditions and more importantly, since the gate or latch must be manually opened, such interference will greatly increase the danger of injury to the operator when a chain is being loaded onto a grab hook.
It is an object of this invention to provide a safety latch for a lifting hook which is capable of opening and closing automatically during loading with no portion of the latch projecting from a side of the hook in either the open or closed position.
It is a further object of this invention to provide a safety latch which is particularly suited for use on a grab hook.
It is another object of this invention to provide a safety latch which has a minimum of parts and is simple and inexpensive to manufacture, as well as being rugged and dependable in use under heavy load conditions.